CT - TCC - Engenharia de Materiais
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Bachelor Thesis Síntese e propriedades fotocatalíticas de niobato de níquel (NiNb2O6) modificado com metais de transição (Zn e Cu)(Universidade Federal do Rio Grande do Norte, 2026-06-26) Duarte, Willian Nascimento; Andrade Neto, Nivaldo Freire de; Motta, Fabiana Villela da; 0000-0002-3523-737X; http://lattes.cnpq.br/9918299069511517; 0000-0003-1421-2904; http://lattes.cnpq.br/4019473456045745; 0009-0007-6847-4324; http://lattes.cnpq.br/7753239496338692; Morais, Débora Ferreira dos Santos; 0000-0002-8801-9720; http://lattes.cnpq.br/6958079215646587The contamination of aqueous effluents by organic pollutants, such as dyes and pharmaceuticals, along with the relative inefficiency of conventional treatment processes, has motivated the development of semiconductors capable of acting in advanced oxidation processes (AOPs), mainly aimed at heterogeneous photocatalysis. In order to evaluate their feasibility for photocatalytic applications, this work aimed to synthesize and characterize pure nickel niobate (NiNb2O6) and nickel niobate doped with transition metals, copper (Cu) and zinc (Zn), at concentrations of 5% and 10%, using the sol-gel method. The samples were characterized by X-ray diffraction (XRD) with Rietveld refinement, field-emission scanning electron microscopy (FEG-SEM) with energy-dispersive spectroscopy (EDS), diffuse reflectance spectroscopy in the ultraviolet-visible region (UV-Vis), and photoluminescence (PL). The photocatalytic activity was investigated through the degradation of the organic contaminants methylene blue (dye) and ciprofloxacin (antibiotic). The XRD results indicated the predominant formation of the orthorhombic columbite NiNb2O6 phase. The morphological analyses showed that copper favored elongated and anisotropic particles, whereas zinc induced more faceted, compact, and heterogeneous morphologies. The optical analyses revealed that the dopants generated intermediate levels within the band gap of NiNb2O6, with a greater reduction in the band gap for the Cu²⁺-doped samples. Photoluminescence confirmed changes in the radiative centers and in the dynamics of electronic recombination. In the photocatalytic tests, the sample doped with 10% copper exhibited the best overall performance, reaching 79% de-gradation of methylene blue after 120 min and 94% removal of ciprofloxacin after 120 min, following a 40 min dark adsorption step, under UVC irradiation. In the pH variation analyses, the basic medium favored dye degradation, while the scavenger tests indicated the relevant participation of photogenerated holes (h⁺) and derived oxidizing species. Thus, the results demonstrate that controlled doping of NiNb2O6 constitutes a promising strategy for modulating the structural, optical, and photocatalytic properties of niobates applied to environmental remediation.Bachelor Thesis Síntese de nanomarcadores superparamagnéticos aplicados à avaliação de integridade de bainhas cimentícias de poços petrolíferos(Universidade Federal do Rio Grande do Norte, 2026-06-26) Fernandes, Sabrina Gabrielle da Silva; Martinelli, Antonio Eduardo; http://lattes.cnpq.br/0022988322449627; https://orcid.org/0009-0001-9911-7967; https://lattes.cnpq.br/9869048785133399; Paskocimas, Carlos Alberto; http://lattes.cnpq.br/2365059843175411; Mendes, Armando Monte; http://lattes.cnpq.br/3173204192281049The structural integrity of cement cementation in oil wells is essential to ensure zonal isolation, operational safety, and the durability of the wells throughout their service life. However, conventional monitoring methods have limitations related to sensitivity, resolution, and the ability to continuously detect failures. In this context, iron oxide nanoparticles stand out as promising materials for the development of smart cementitious systems designed for structural monitoring. Thus, the objective of this study was to synthesize iron oxide nanoparticles via a hydrothermal route, investigating the influence of synthesis pressure and functionalization on their structural, morphological, and magnetic properties. The nanoparticles were obtained via conventional and pressurized hydrothermal synthesis, with and without surface functionalization. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and vibrating sample magnetometry (VSM). Overall, the results demonstrated that the synthesis route and functionalization influence the structural, morphological, and magnetic properties of the nanoparticles. These materials show potential for future applications in smart cementitious systems designed to monitor the structural integrity of cement liners in oil wells.Bachelor Thesis Influência de rotas de síntese nas propriedades de suportes de alumina (Al2O3) direcionados à catálise ambiental(Universidade Federal do Rio Grande do Norte, 2026-06-26) Borges, Raony Assunção da Silva; Melo, Dulce Maria de Araújo; Motta, Fabiana Villela da; http://lattes.cnpq.br/9918299069511517; http://lattes.cnpq.br/3318871716111536; https://lattes.cnpq.br/0080585246538419; Paskocimas, Carlos Alberto; Medeiros, Rodolfo Luiz Bezerra de Araújo; Oliveira, Ângelo Anderson Silva deThe mitigation of greenhouse gases via CO2 methanation and dry methane reforming requires stable heterogeneous catalysts exhibiting high resistance to thermal sintering and carbon deposition. The alumina support plays a pivotal role in active phase dispersion and the overall stability of the catalytic system. This study investigated the influence of different synthesis routes on the morphological, textural, and structural properties of pure alumina supports and catalysts impregnated with 10 wt% Ni. The supports were synthesized via sol-gel, Pechini, hydrothermal, and microwave-assisted combustion methods, and compared against a commercial α-Al2O3 reference. The materials were characterized by X-ray diffraction (XRD) with Rietveld refinement, N2 adsorption/desorption (BET), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The results revealed the predominant formation of transition alumina phases, particularly γ-Al2O3, in the synthesized samples. The Pechini method yielded the support with the highest specific surface area (182.36 m2·g–1) and the catalyst with the smallest average NiO crystallite size (14.24 nm). Microwave-assisted combustion produced a spongy, highly permeable macroporous structure. FTIR analyses indicated strong metal-support interactions, evidenced by the consumption of surface hydroxyl groups and the formation of a NiAl2O4 spinel phase, which was absent in the commercial alumina. In conclusion, alternative synthesis routes, particularly Pechini and microwave-assisted combustion, produce supports with superior nickel dispersion and anchoring capabilities, representing promising candidates for environmental catalysis applications.Bachelor Thesis Desenvolvimento, caracterização e avaliação de minérios de ferro modificados com cálcio: influência da formação de ferritas de cálcio no desempenho em Chemical Looping Combustion(Universidade Federal do Rio Grande do Norte, 2026-06-19) Silva, Jeniffer Bomfim da; Melo, Dulce Maria de Araújo; Motta, Fabiana Villela da; http://lattes.cnpq.br/9918299069511517; http://lattes.cnpq.br/3318871716111536; https://orcid.org/0009-0000-2503-7123; http://lattes.cnpq.br/9631128365143457; Santiago, Rebecca Araújo Barros do Nascimento; https://orcid.org/0000-0002-4185-9802; http://lattes.cnpq.br/1877747013074680; Paskocimas, Carlos Alberto; http://lattes.cnpq.br/2365059843175411The growing energy demand associated with the need to mitigate greenhouse gas emissions has driven the development of technologies capable of generating energy with inherent CO2 capture, such as Chemical Looping Combustion (CLC). In this context, this study evaluated the potential of a natural iron ore from the state of Ceará, Brazil, and its calcium-modified counterpart as oxygen carriers (OCs) for CLC applications. Calcium ferrite was synthesized by modifying the iron ore with CaO derived from eggshell waste, aiming at the formation of the Ca2Fe2O5 phase. Three synthesis routes were investigated to evaluate the influence of milling and thermal treatment on ferrite formation. The oxygen carriers were characterized by X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), mechanical strength tests, Temperature-Programmed Reduction (TPR), and Thermogravimetric Analysis (TGA). The iron ore contained 88.27 wt.% Fe2O3, while the calcium ferrite contained 63.33 wt.% Fe2O3 and 30.98 wt.% CaO, indicating compatibility with the desired stoichiometric composition. XRD results confirmed the formation of calcium ferrite through the optimized synthesis route. Mechanical strength values of 4.6 N and 4.7 N were obtained for the iron ore and calcium ferrite, respectively, indicating their potential application in fluidized-bed systems. TPR analyses revealed active redox behavior for both materials. Reactivity tests performed at 900 °C showed reversible redox behavior under H2 and CH4 atmospheres for both oxygen carriers. The iron ore exhibited a higher oxygen transport capacity, reaching a Roc of 3.77%, whereas the calcium ferrite reached a Roc of 1.41% due to its lower relative Fe2O3 content. In contrast, the calcium ferrite achieved higher conversion values during the redox cycles, reaching Xred values of 4.85 with H2 and 1.99 with CH4, indicating greater oxygen availability during the reduction reactions. The results demonstrate that the modification of iron ore with CaO enabled the production of an oxygen carrier with promising redox behavior for application in Chemical Looping Combustion.Bachelor Thesis Reaproveitamento de resíduos de botões naturais: um estudo de caso(Universidade Federal do Rio Grande do Norte, 2026-06-25) Nóbrega, Luiz Felipe Pereira de Medeiros; Mashhadikarimi, Meysam; https://orcid.org/0000-0003-1449-3654; http://lattes.cnpq.br/9371689730074581; https://orcid.org/0000-0001-7337-1919; http://lattes.cnpq.br/2593969877749292; Paskocimas, Carlos Alberto; Farias, Morena Brito de; Vaz, Luiz Carlos NunesIn coastal countries such as Brazil, mariculture, or the cultivation of marine organisms, represents an economic activity of great importance, especially for traditional and riverside communities. One of the products derived from mariculture is mother-of-pearl. Mollusks secrete nacre in layers, a substance rich in calcium carbonate, forming their shells. This material produced by the animal can be used in several activities such as decoration, costume jewelry, handicrafts, and even button manufacturing. During the production of buttons using mother-of-pearl as raw material, a large portion of this material is underutilized, with losses reaching up to 70 wt.%. The present work aims to explore the reuse of this waste for the production of calcium oxide, commonly known as quicklime. This compound, widely used in engineering, has applications in the production of paints, cement, and in soil pH correction. The research began with structural (XRD), microstructural (SEM), particle size (laser granulometry), chemical (XRF), and thermal (TG/DTA) characterization analyses. Subsequently, a calcination process was carried out at 900°C under an oxidizing atmosphere, similar to the industrial quicklime production process. After this procedure, new XRD and SEM analyses confirmed the formation of the new phase. The obtained results clearly demonstrated the technical feasibility of using shell waste as a natural and renewable raw material for calcium oxide production, thus contributing to a sustainable alternative for resource utilization and the reduction of potential environmental impacts.Bachelor Thesis Efeito da lama da areia no desempenho de argamassas colantes(Universidade Federal do Rio Grande do Norte, 2026-02-10) Quirino, Daniely de Sousa; Silva, Bismarck Luiz; Paskocimas, Carlos Alberto; Silva, Bismarck Luiz.; Paskocimas, Carlos Alberto.; Costa, Maria Aline Silva da.This study aims to analyze the effect of sludge in sand on the performance of adhesive mortars, within the scope of Quality activities. The presence of this fine fraction can modify fundamental parameters of the mortar, influencing its workability, water retention, open time, adhesion, and mechanical strength. The research was conducted through normative tests applied to different samples, allowing us to quantify the influence of sludge on the material's physical and mechanical properties. Preliminary results show that variations in sludge content directly alter the behavior of mortars, potentially improving workability under certain conditions, but compromising strength and stability when present in excess. Analyzing these impacts provides technical support for defining acceptable limits, supporting quality control criteria, and guiding adjustments to production processes. It is concluded that monitoring sludge in sand is essential to ensure consistent performance of adhesive mortars, in addition to contributing to optimizing the use of raw materials and implementing more efficient and sustainable industrial practices.Bachelor Thesis Reaproveitamento de resíduos laboratoriais a base de vidro de borosilicato para produção de filtro para suporte a óxidos(Universidade Federal do Rio Grande do Norte, 2025-12-01) Oliveira, Madson Luiz Galliz; Paskocimas, Carlos Alberto; Almeida, Cláudio Romero Rodrigues de; Farias, Morena Brito de; Murriguima, Paulino Vasco MarianoThe disposal of laboratory solid waste, specifically damaged or unused borosilicate glassware, represents an environmental challenge and a waste of material with excellent thermal and chemical properties. Aiming to mitigate this impact and add value to the waste, the present work investigates the repurposing of borosilicate glass for the manufacture of porous ceramic supports intended for application as filters for the immobilization of functional oxides (antibacterial, photocatalytic, and catalytic). The methodology adopted was based on the sacrificial phase replica technique, using a material that was subsequently removed. The recycled glass was ground and sieved (50 mesh) and mixed with a soluble inert material (15 mesh) in three distinct proportions: 40%, 50%, and 60% relative to the glass mass. The specimens were compacted via uniaxial pressing at 80 MPa and sintered at 825°C for 120 minutes, with slow furnace cooling. The final porosity was obtained through the leaching of the inert material in distilled water at 80°C for 48 hours. The characterizations performed (SEM, EDS, OM, and XRD) demonstrated the method's efficacy. Morphological analyses indicated a linear increase in the average pore size proportional to the amount of inert material, ranging from 69.55 μm (40% sample) to 210.95 μm (60% sample), with apparent porosity reaching 55.99% in the sample with the highest concentration. Furthermore, impregnated samples presented a slight alteration in the EDS analysis, showing that oxide impregnation occurred successfully. The result observed via XRD was the unexpected recrystallization of the amorphous glass matrix into the crystalline $\alpha$-cristobalite phase, induced by the sintering thermal cycle and slow cooling. It is concluded that the developed processing allows effective control of pore morphology and the obtainment of supports with interconnected channels. The formation of the $\alpha$-cristobalite phase confers thermal stability to the assembly, validating the recycled material as a promising substrate for technological applications in filtration and catalysis.Bachelor Thesis Influência do efeito da rota de processamento nas perdas magnéticas de dois aços baixo carbono semiprocessados(Universidade Federal do Rio Grande do Norte, 2025-12-02) Rodriguez, Jade Oliveira Palevicius; Correa, Marcio Assolin; Castro, Nicolau Apoena; Bohn, Felipe; Rodrigues, Flavio José SaraivaThis work investigated the influence of box annealing and continuous annealing on the microstructure and magnetic properties of two low-carbon electrical steels, identified as A and B. The characterization was carried out through X-ray diffraction (XRD), optical microscopy (OM), Vibrating Sample Magnetometry (VSM), and Magnetic Barkhausen Noise (MBN). The results showed that both steels exhibited the formation of a superficial hematite layer after annealing, which was more pronounced under box-annealing conditions. Grain growth evolution determined the magnetic performance of the samples. Steel A exhibited more continuous annealing, resulting in more homogeneous microstructure. Hysteresis losses decreased with increasing grain size, with reductions greater than 45% for A and 68% for steel B. THe MBN measurements confirmed the decrease in identifying the predominant magnetization phenomenon in the samples based on the MBN response. It was concluded that steel B exhibited better performance when processed through continuous annealing, whereas steel A showed a better response to box annealing.Bachelor Thesis Aço API 5L X70: mapa de dureza como ferramenta auxiliar de análise da efetividade do passe de revenimento(Universidade Federal do Rio Grande do Norte, 2025-12-05) Dantas, Vinícius Medeiros de Oliveira; Barra, Sérgio Rodrigues; http://lattes.cnpq.br/8696527355956341; Castro, Nicolau Apoena; Silva, João Lucas Araujo da; Nascimento, Alexandre Saldanha doThe structural integrity of pipelines intended for oil and gas transport is frequently challenged during fabrication by welding, a process that induces severe thermal cycles in the API 5L X70 high-strength low-alloy (HSLA) steel. The rapid cooling in the Heat-Affected Zone (HAZ), specifically in the Coarse-Grained Heat-Affected Zone (CGHAZ) sub-region, favors the formation of brittle, high-hardness microconstituents, such as untempered martensite, drastically increasing the material's susceptibility to critical failures, including Hydrogen Induced Cracking (HIC) and stress corrosion cracking. As an efficient and cost-effective alternative to Post-Weld Heat Treatment (PWHT), this work investigated the efficacy of the Temper Bead Welding technique, applied in a double layer. The experimental methodology employed the automated MAG welding process (Gas Metal Arc Welding), systematically varying the heat input (levels H1, H1.5, and H2) and the lateral overlap rates of the beads (10%, 35%, and 50%). The technique's validation was based on the construction of Vickers Microhardness Maps (Hardness Mapping) and optical microscopy, providing a detailed visual analysis of the joint's mechanical anisotropy, superior to conventional linear measurements. The results demonstrated that the method's effectiveness is dependent on the correct parameterization of heat input and pass overlap, taking into account the bead width. The configuration with 35% overlap associated with the intermediate heat input (H1.5) exhibited superior performance. This condition ensured that the tempering isotherm effectively covered the CGHAZ of the previous pass, promoting microstructural refinement and the decomposition of hard phases into more tough constituents. It is concluded that the technique, when optimized, restores the hardness to safe levels required by international standards (below 22 HRC), validating hardness mapping as an indispensable tool for ensuring integrity in multipass welding.Bachelor Thesis Avaliação do potencial uso do poliacrilato de sódio em condicionamento de solo(Universidade Federal do Rio Grande do Norte, 2018-06-21) Medeiros, Múcio Dantas de; Viana, Kaline Melo de Souto; Motta, Fabiana Villela da; 0000-0002-3523-737X; 9918299069511517; 0009-0006-1596-0428; 3289446495842859; 0000-0003-2863-5780; 0106007830851676; Castro, Vera Lúcia Lopes de; 0009-0006-1596-0428; 5179660919760767; 0000-0002-3523-737XThe hydroabsorbent polymer is a material that defines a group of polymeric materials that has a high water retention in its three-dimensional network. The use of this polymer is an option for absorber and/or charger devices for controlled release of water and nutrients/minerals, releasing water and/or nutrients slowly, fixing and retarding the presence in soil to reduce leach losses or toxicity. These characteristics can be attributed to the fact that its presence modifies adverse physicochemical properties of the soil. The present study aimed at evaluating the qualitative efficiency of sodium polyacrylate (PAS) found in disposable diapers used as a soil conditioner in the semiarid region through the characterization of thermal and soil analyzes by means of porosity and granulometry determination. The PAS was removed from the diapers and a sample preparation for the thermal analyzes of Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry and differential thermal analysis. Based on the results obtained and on information found in the literature, the soil is composed of 92,3% of sand, 6% of clay and 1.,% of silt, and presents a total porosity of 51,8%. It was observed that PAS removed from diapers has been shown to have a semicrystalline microstructure, has amine and polyacrylate groups in your composition, having a Tg of 445°C, a Tm of 532°C and degrading at 864°C. Therefore, the results indicate that PAS is a strong candidate for use of alluvial soil synthetic conditioner.Bachelor Thesis Estudo do reparo induzido por pulsos elétricos do aço API x65 laminado a quente(Universidade Federal do Rio Grande do Norte, 2025-12-02) Souza, Maurício Moreira de; Peres, Mauricio Mhirdaui; Castro, Nicolau Apoena; Ferreira, Jetson LemosThe oil and gas industry has undergone successive technological advances aimed at improving efficiency in extraction, transportation and refining, establishing itself as one of the most economically significant sectors worldwide. In this context, the development of materials and equipment suited to rigorous operational conditions becomes essential, and the API 5L X65 steel used in this study is widely employed in the petroleum industry, offering an excellent combination of mechanical strength, hardness, and performance under high pressures and temperatures, as well as good cost-effectiveness for pipeline applications. However, wear remains responsible for a large portion of pipeline failures, especially due to the formation of microcracks and microfractures that reduce mechanical integrity and can propagate rapidly; to simulate this behavior, Charpy type A specimens were fabricated and subsequently subjected to fatigue testing to generate standardized microcracks in the notch, reproducing real service conditions. Although different strategies exist for mitigating such defects, induced repair has emerged as a promising alternative, as this method promotes the migration of atoms to damaged regions, favoring stress relief and microstructural regeneration. In this work, an innovative induced repair method based on electrical pulses (EPT) is proposed, where the passage of pulsed electrical current enhances atomic diffusion and assists the movement of dislocations, contributing to material recovery. The effectiveness of the process was evaluated by impact testing, comparing toughness before and after pulse application, and the use of electrical pulses thus shows potential as an efficient alternative to conventional heat treatments, as demonstrated mainly by the impact test results, offering advantages such as localized heating, reduced processing time, stress relief, and possible regeneration of microscopic defects.Bachelor Thesis Traçadores ópticos aplicados ao MUD Logging(Universidade Federal do Rio Grande do Norte, 2025-07-09) Rodrigues, Karolynne Emanuelle Alves; Martinelli, Antonio Eduardo; Mendes, Armando Monte; http://lattes.cnpq.br/1735913659639278; Campos Júnior, Jose Ribamar; Paskocimas, Carlos AlbertoBachelor Thesis Efeito da dopagem com elementos de transição nas propriedades estruturais e ópticas do composto Ce2(MoO4)3(Universidade Federal do Rio Grande do Norte, 2025-01-07) Castro, Symone Leandro de; Delmonte, Mauricio Roberto Bomio; http://lattes.cnpq.br/9558299312183852; http://lattes.cnpq.br/3750857608670963; Melo, Alan Jones Lira de; Santiago, Anderson de Azevedo GomesDue to their promising properties in various fields of knowledge, molybdate-based materials, especially cerium molybdate Ce₂(MoO₄)₃, have been attracting considerable attention in the field of nanotechnology. Thus, the present work aimed at the synthesis and study of the cerium molybdate semiconductor Ce₂(MoO₄)₃ in both pure and transition metal-doped forms, to observe the influence of dopants on the physical and optical properties of the synthesized nanomaterials. For this purpose, the nanomaterials Ce1.8A0.2(MoO4)3 (A = Ag+1, Zn+2, Y+3, Ti+4, Nb+5) were synthesized using the microwave-assisted hydrothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FEG-SEM), UV-vis spectroscopy, and photoluminescence spectroscopy. The diffraction patterns confirmed the formation of pure Ce₂(MoO₄)₃ without secondary phases. For the doped materials, the successful incorporation of the respective dopant atoms into the crystalline structure was observed. The FEG-SEM images revealed the influence of the dopant ion on the final morphology of the materials, showing changes from a nanoplate-like morphology to an oval, football-like shape. Additionally, variations in the band gap energy of the doped materials compared to pure Ce₂(MoO₄)₃ were observed, indicating the creation of intermediate levels between the valence band and the conduction band due to the insertion of dopant ions into the Ce₂(MoO₄)₃ structure. The photoluminescence spectra demonstrated a reduction in photoluminescence intensity and a broadening of the emission band within the visible spectrum, possibly due to a decrease in the electron-hole recombination rate. The broadening in the visible spectrum, along with CIE data and quality tests, confirmed that the doped materials are promising for high-quality cool white light emission for commercial environments. The samples Ce1,8Zn0,2(MoO4)3, Ce1,8Y0,2(MoO4)3 and Ce1,8Ti0,2(MoO4)3 exhibited x and y coordinates close to 0.33, CCT above 6000K, CRI greater than 96, and color purity lower than 7.12%. Based on these results, it is concluded that the microwave-assisted hydrothermal synthesis method was efficient for obtaining the nanomaterials Ce1.8A0.2(MoO4)3 (A = Ag+1, Zn+2, Y+3, Ti+4, Nb+5) and that the photoluminescent properties of the doped nanomaterials present potential applications for the fabrication of WLEDs (white light-emitting diodes) due to their white light emission.Bachelor Thesis Avaliação do efeito da solubilização e do envelhecimento na estrutura cristalina e na microdureza da liga Al-Mg AA5083(Universidade Federal do Rio Grande do Norte, 2024-06-24) Holanda, Eloam Jessica Nunes; Peres, Maurício Mhirdaui; Castro, Nicolau Apoena; http://lattes.cnpq.br/3740711945494961; http://lattes.cnpq.br/3068024292581677; https://lattes.cnpq.br/5676779786837514; Silva, Bismarck Luiz; http://lattes.cnpq.br/4377238190630005; Gonçalves, Rennáh Francisco Figueiredo; http://lattes.cnpq.br/5292990047030419The AA5083 Al-Mg alloy is widely used in various industrial applications due to its excellent combination of mechanical properties and corrosion resistance. However, to ensure its optimal performance or to recover these properties in challenging operational environments, such as in the oil and gas industry, a potential solution lies in performing heat treatments. This study investigates the microstructure and microhardness of 5083 H112 alloy samples subjected to solution treatment and aging at different temperature and time combinations. Analyses were conducted using scanning electron microscopy (SEM-FEG with EBSD and EDS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and Vickers microhardness testing to analyze how changes in the crystalline structure affect mechanical properties. The results indicate that the original sample, partially strain-hardened by rolling, showed signs of incomplete recrystallization, Al-a grains with high magnesium content in solid solution, suggesting a metastable state, along with Mg-rich precipitates and the Al6(Fe, Mn) phase. Solubilized samples exhibited grain growth due to thermal activation and restoration of the original hardened material's crystal structure. On the other hand, samples aged under different conditions showed a higher quantity of precipitates Al6Fe compared to others, increasing microhardness over time. However, work hardening proved more effective in strengthening the material compared to thermal treatments.Bachelor Thesis Análise de aspectos de borda de corte em aço avançado Ferrita-Bainita via Microscopias Óptica e Eletrônica de Varredura(Universidade Federal do Rio Grande do Norte, 2024-06-24) Peixoto, Killdery Fernandes; Castro, Nicolau Apoena; https://lattes.cnpq.br/1537818421633631; Peres, Mauricio Mhirdaui; Gonçalves, Rennáh Francisco FigueiredoBachelor Thesis Análise microestrutural de amostras aço de dutos de produção e sistema de injeção de água produzida em campos de petróleo maduros on-shore(Universidade Federal do Rio Grande do Norte, 2024-06-24) Silva, Erick Vale Oliveira da; Castro, Nicolau Apoena; Peres, Mauricio Mhirdaui; Gonçalves, Rennáh Francisco FigueiredoBachelor Thesis Síntese de nanopartículas de alumina e sua influência nas propriedades rocha-fluido em reservatórios de óleo(Universidade Federal do Rio Grande do Norte, 2024-06-21) Rocha, Camila Louyse Oliveira da; Martinelli, Antonio Eduardo; Rodrigues, Marcos Allyson Felipe; https://orcid.org/0000-0002-8936-5705; http://lattes.cnpq.br/5453593230706116; https://orcid.org/0000-0003-3885-9104; http://lattes.cnpq.br/0022988322449627; https://orcid.org/0000-0003-1531-4099; https://lattes.cnpq.br/7793908717511173; Oliveira, Gregory Vinicius Bezerra de; http://lattes.cnpq.br/5656895709723231; Campos Júnior, José Ribamar; http://lattes.cnpq.br/5289859159562200The adsorption and retention of heavier oil fractions on the rock surface over time as a result of oil aging and exposure poses a challenge for the oil industry in terms of extraction efficiency. Conventional methods exhibit limited sweep efficiency, leaving part of the oil trapped in the microporous regions of the rock. The use of alumina nanoparticles (Al2O3) has proven to be attractive for Enhanced Oil Recovery (EOR) processes due to their properties such as reducing interfacial tension (IFT) and oil viscosity, in addition to the possibility of reversing the wettability of the rock. Alumina can be obtained by various chemical routes, with the hydrothermal route standing out due to better control of parameters such as temperature, time, and pressure, which influence the characteristics of nanomaterials. This study focuses on the synthesis of γ-Al2O3 nanoparticles by thermal treatment of boehmite (AlOOH), obtained via hydrothermal synthesis, and investigates the impact of these nanoparticles on IFT and rock wettability. Material characterization was performed using XRD, FTIR, SEM-FEG, and BET techniques. Nanofluids with different concentrations of Al2O3 were also produced and tested for their interaction with medium (°API = 22,36) and heavy oils (°API = 26,68). The results showed the production of Al2O3 nanoparticles with nanoplace like morphology and low agglomeration. A greater influence on IFT modification was observed in nanofluids with lower concentrations for medium oil and higher concentrations for heavy oil. Alumina also demonstrated potential for wettability inversion in sandstone reservoirs, emphasizing its viability as an EOR technique.Bachelor Thesis Especificação de mola pneumática para uso em Veículos Leves sobre Trilhos (VLTs): um estudo de caso na CBTU-RN(Universidade Federal do Rio Grande do Norte, 2024-04-25) França, Stefany Felix de; Silva, Bismarck Luiz; Peres, Maurício Mhirdaui; Carvalho, Cássia CarlaBrazil is still heavily dependent on road transportation, as exemplified in 2018 by the truck drivers' strike, which disrupted the delivery of goods and supplies, affecting society as a whole. The railway sector offers an alternative route to minimize this dependency, one that needs further improvement. The national railway network was established in 1854 as a new means of transportation, bringing socio-economic benefits and technological development. In Rio Grande do Norte (RN), railways transport an average of 14,000 people daily using trains and Light Rail Vehicles (LRVs). The latter were introduced to the RN railway line by the Brazilian Urban Transport Company (CBTU) in 2014, becoming the main rail transport vehicle. As LRVs have only recently been incorporated into Brazil, there is still a shortage of technical support and replacement parts for maintenance. In this context, the aim of this study is to specify a pneumatic spring used by CBTU (Natal) in the Mobile 3 LRVs, as well as to present and discuss constituent materials, operation, and applicability of pneumatic springs, and possible maintenance and procurement routes. A detailed and critical bibliometric survey was conducted in the Web of Science database, in addition to contacts with transportation sector companies and CBTU (Natal) staff. A proposal for a purchasing, usage, and disposal cycle was also discussed.Bachelor Thesis Produção e análise de filamentos não convencionais de PP, PA6 e PMMA para impressão 3D(Universidade Federal do Rio Grande do Norte, 2024-03-08) Lima, Luís Eduardo da Silva; Ito, Edson Noriyuki; Vilar, Caroline Dantas; Gomes, Felipe Pedro da Costa; Silva, Alice da Costa3D printing through Fused Deposition Modeling (FDM) is widely used across various sectors of society, yet few thermoplastic filaments dominate the market. With increasing demands for alternatives to conventional filaments, this work aims to produce and evaluate polypropylene (PP), polyamide 6 (PA6), and poly(methyl methacrylate) (PMMA) filaments to achieve a wider range of costs, properties, and applications. The melt flow index measurements of the materials were verified using a Ceast Melt Flow plastometer to assess the rheology of each material and the ideal temperature ranges for subsequent processing. The materials were plasticized in a single-screw extruder for filament production and exhibited good flow during extrusion, allowing for diameter control of the filaments at 1.75 mm. Subsequently, V-type test specimens of PP, PA6, and PMMA were produced according to ASTM D638 standard using 3D printing, varying the layer deposition configuration. The variation occurred in the deposition angle: 0° (oriented layers) and 45° (alternating layers). Additionally, type I test specimens were fabricated via injection molding, which were laser-cut into V-type test specimen shapes for characterization under the same conditions and comparison between molding techniques. The samples were characterized through uniaxial tensile testing and scanning electron microscopy (SEM). Samples printed in semicrystalline polymer showed a greater tendency to warping due to their contraction characteristics upon cooling; however, processing parameters were adjusted. Adjustments in processing configuration, such as temperature changes, air entry into the interior of the 3D printer, and adhesion of the molten polymer to the print bed, enabled obtaining good quality in the produced test specimens. The printed test specimens exhibited mechanical property results close to those produced by injection molding, indicating that FDM 3D printing can be used to produce parts with good mechanical properties.Bachelor Thesis Caracterização da liga de alta entropia CrMnFeCoNi obtida através de moagem mecânica de alta energia(Universidade Federal do Rio Grande do Norte, 2023-12-11) Souza, Fernando Oliveira do Nascimento; Mashhadikarimi, Meysam; Silva, Bismarck Luiz; Araújo, Kívia Fabiana Galvão deHigh Entropy (LAE) alloys are metallic materials that are standing out in recent years, due to the obtaining of a material with important properties, such as high hardness, corrosion resistance, wear, thermal stability and fatigue resistance, enabling them use in different fields of application. Unlike classic metallurgy where commonly used alloys are based on a single main element, high entropy alloys are multicomponent alloys, containing five or more elements in almost equal (echistomic) proportions and feature simple crystalline structures. In this sense, the objective of the work was to produce a high entropy alloy, consisting of chromium (CR), manganese (MN), iron (Fe), cobalt (CO) and nickel (NI), through high energy grinding. The obtained league was characterized by scanning electron microscopy (SME), energy dispersion spectroscopy (EDS) and X-ray diffraction (DRX), aiming to investigate alloy phase formation. In addition, initially a computational simulation of phase formation was made through Pandattm software, in order to analyze the feasibility of formation of the CRMNFeconi Echiatomic League. The results showed that the high energy grinding method employed in this work was efficient to obtain the high entropy alloy. Since the diffractograms showed well -defined diffraction points, thus revealing the formation of a cubic cubic crystal phase of centered face. Three LAE samples at different times, 5h, 10h and 15h, were samples, with the sample with 15 hours of grinding that obtained the best result, as it presented the main peak of the league, as well as a decrease in the intensity of the peaks related to secondary phases. Through the MEV it was possible to observe the change in morphology, as well as the evolution of miscegenation of the different posts and league formation, noting that grinding time was an important factor for obtaining and greater homogenization of the alloy.